Effective early intervention depends on reliable screening of risk for communication impairments as soon as possible. Established infant communication risk factors include poor attention, gestures, social connectedness, exploratory play, and speech. Although these risk factors can be detected by 12-18 mos. and reliably predict later language and social disorders, attempts to detect similar risk factors in infants 2-1 mos. have been unsuccessful because of limitations in available screeners that include only 2-3 items for preintentional communication (i.e., reactive or active infant communication behaviors not directed toward listeners). There are no available screeners that provide normed and sensitive data on preintentional communication and reflect evidence-based predictors that discriminate infants at risk for communication impairments before 12 mos. When practitioners cannot detect infant behaviors known to be associated with communication risk, they cannot target early intervention to children with the greatest needs and potential for improvement. If we can identify communication risk early enough, we can intervene in skills that predict communication impairments, mitigate effects of primary impairments in children, and reduce potential for secondary impairments that affect communication and other life skills. The plan for this project is to develop a predictive, sensitive, modality- independent screener to detect communication risk in preintentional infants 2-12 mos. (Communication in Infants and Social Screener, or CISS). Pilot research by the Principal Investigator showed that a short set of qualitative judgments could reliably discriminate infants age 2-12 mos. with typical development (TD) from those who later showed communication impairment. The easy qualitative judgments on the CISS have been derived from the PI's comprehensive assessment of preintentional infant communication, the Infant Social and Communication Behavior Scales, and correspond to behavior clusters for the leading toddler communication assessment, the Communication and Symbolic Behavior Scales Development Profile - Infant Toddler Checklist (CSBS DP-ITC); Wetherby & Prizant, 2002). A sensitive and specific screener for communication risk could justify the early involvement of speech-language pathologists for infants as well as for older children with complex communication needs. We will revise the pilot CISS to detect communication risk factors in infants 2- 12 mos. with and without known disabilities, score retrospective video data from preintentional infants with and without known disabilities, and test new samples of 130 TD or at-risk preintentional infants at 2-12 mos., to achieve these specific aims: Identify CISS domains that discriminate preintentional infants at risk for communication disabilities from TD infants using video databases. Develop CISS clusters and a composite that discriminate at-risk disability status in existing infant samples with sensitivity and specificity. Establish reliability and validity of CISS cluster and composite scores in new as well as videotaped samples of TD and at-risk infants using correlational analyses, including exploratory factor analysis and cluster analysis.